Radiation-induced Pulmonary Disease

This article discusses the natural history, clinical epidemiology, diagnosis, and treatment of radiation-induced lung diseases (RILDs). Furthermore, we review current experimental developments and assess potential areas for future investigation. Radiation therapy (RT) is a key component of the approach to the treatment of thoracic neoplasms. The use of radiation for the treatment of cancer exploits the preferential cytotoxicity of radiation to cells with high mitotic index. By the same principle, non-neoplastic cells with high mitotic index are also vulnerable to the deleterious effects of radiation. As a consequence, RT to the lung culminates in significant injury to normal cells with high mitotic index such as vascular endothelial cells and alveolar type II pneumocytes. The clinical manifestations of radiation-induced lung injury fall into two categories, acute radiation pneumonitis (RP) and radiation-induced lung fibrosis (RIF) which is a late sequelae of RT. Epidemiological analyses reveal that radiationmediated lung injury is amplified by many factors, such as radiation dose–lung volume relationships, concomitant use of chemotherapy, and the abrupt withdrawal of previously instituted steroid therapy. The cornerstone of the management of RILDs is prevention that is accomplished through surveillance of lung function, prompt evaluation of respiratory symptoms, and the early institution of steroids upon making a diagnosis of RP.